You wouldnt want to only rely on helical piers for a free standing tower.
If its a guyed tower the guys resist nearly all of the lateral load so the
base only has to support the dead weight of the tower so in that case you
could use helical piers for everything.
The pressure I referred to is basically the torque. Its read out on a
pressure gauge on the hydraulic line and that pressure calibrated to a
certain torque.
I suggest calling your building department, if you have to pay for a permit
you might as well do it how they want you to. I doubt this will be their
first pier inspection.
The best way to verify a pier is to try to pull it out. If you can put two
times the design load on the pier and it doesnt fail then it is properly
designed and jnstalled. This is something your contractor would do. They
will know or should know if it will be required or not.
Brian
KF7OVD
On Jul 10, 2014 6:37 PM, "Richard (Rick) Karlquist" <richard@karlquist.com>
wrote:
> The screw in anchors, if used, would be for guying.
> I guess you are saying that I must make the base big
> enough to handle lateral force and I can't use the
> guy anchors to hold the base in place. Got that.
> So I have a choice of having my engineer watch
> and certify and/or inviting the inspector watch
> himself.
>
> Is the pressure you are talking about the amount of
> force to push the anchor in (an axial force) or the
> amount of torque to turn the anchor in? With the
> hand installed ones, only torque is needed. The
> screw pulls itself into the ground.
>
> Rick N6RK
>
> On 7/10/2014 3:24 PM, Brian Amos wrote:
>
>> As for the utilities usually the municipality doesn't inspect their
>> installations as they are self regulating. The "screw anchors" ie
>> "helical piers" are installed to a certain torque which the software
>> tells the installation contractor he must meet. As a soil engineer I
>> have many times had to "inspect" the installation where I watch the
>> pressure gauge and make sure they make it to the required pressure
>> (which they tell me) for each pier and then I have to send a document
>> to the owner stating that it complies with the design and put my stamp
>> on it. I'm not a big fan of that setup as I don't do the engineering
>> but I have to certify that it will hold up. It drives me nuts
>> actually. For a residential purpose I would guess that you just tell
>> the building official when you will be installing it and they can come
>> and watch. That is the only way to really inspect them.
>>
>> BTW: Is this for supporting the tower? Or is it for the guys? If it's
>> for the tower I suspect you will need at least one per leg and it must
>> be a large tower to keep them at least 3 screw diameters apart to
>> prevent interaction. This type of support provides virtually no
>> lateral resistance (especially the square chance bars that have no
>> soil contact anywhere but the helix, they are all tension and
>> compression, so for guy supports they work great, but not so well for
>> a foundation. I suspect that the building official won't care about
>> inspecting screws for a guying system. They usually only care about
>> the foundation itself.
>>
>> Brian
>> KF7OVD
>>
>> On Thu, Jul 10, 2014 at 2:21 PM, Jim Lux <jimlux@earthlink.net> wrote:
>>
>>> On 7/10/14, 10:29 AM, Richard (Rick) Karlquist wrote:
>>>
>>>>
>>>> Has anyone had experience getting a building permit
>>>> for a tower with screw in earth anchors? How does
>>>> it get "inspected". There is no empty hole for
>>>> the inspector to look at. Do you show him the anchor
>>>> before insertion? If you have an authorized AB
>>>> Chance installing contractor put in the anchor,
>>>> do they issue a certificate that you can show the
>>>> inspector? In a sense, this contractor is also
>>>> the engineer and building inspector all in one.
>>>>
>>>>
>>> could it be more like a material and process inspection?
>>> You have the paperwork showing you have the anchor and the mfr's
>>> paperwork
>>> showing what its properties are.
>>> Then you have paperwork showing you did the installation appropriately
>>> (e.g.
>>> if you used a truck mounted drive, it gives a reading of the torque as it
>>> drove it)
>>>
>>>
>>> The only time I've had an "official" inspection of a structure using
>>> screw
>>> in anchors it was for a temporary installation, and the guy came out,
>>> looked
>>> at the plans, looked at the erected contraption, verified that what we
>>> had
>>> built matched the plans, and said "go for it".
>>>
>>> Granted it was in an area and application where failure would hurt nobody
>>> but ourselves.
>>>
>>> What do utilities do when installing poles with these anchors? I find it
>>> hard to believe that the city sends out an inspector to watch them plant
>>> every pole and its guys.
>>>
>>> _______________________________________________
>>>
>>>
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